Convection towers

ABSTRACT

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

The invention is a result of a contract with the Department of Energy(Contract No. W-7405-ENG-36).

BACKGROUND OF THE INVENTION

The present invention generally relates to air pollution control, and,more particularly, to the large scale scrubbing of pollutants from air.

One of the great problems currently facing this country, and indeed theworld, is that of air pollution. The emissions from pollution producingplants, homes, airplanes and automobiles produce potentially harmfulair, particularly in and around large cities. Cleaning this air after itis in the atmosphere is a formidable task. Scubbers on smoke stacks,unleaded gasoline, and carpooling plans seek to reduce the level ofcontamination, but do nothing towards cleaning the pollution that doesreach the atmosphere.

Areas such as Los Angeles and Mexico City have pollution situations thatcan make the air unfit or even dangerous to breathe. Althoughsubstantial efforts have been made to assess the dangers of suchpollution, and to find solutions, these efforts have not yielded a greatdeal of improvement. To solve these pollution problems, an efficient,large scale and economical system is needed.

The present invention does provide a means for cleansing pollution fromthe air, and accomplishes this through the use of convection towers.These towers are capable of economically removing particulate matter,and reducing the level of carbon dioxide and other gases. Variousembodiments of the invention are also capable of producing electricityand large quantities of fresh water.

By way of example, the Los Angeles basin contains approximately 15,000square kilometers of land, with most of the area's pollution beingcreated in an area of only 3,000 square kilometers. The pollution depthbelow the inversion layer is normally approximately 500 meters, so it isonly necessary to clean about 1,500 cubic kilometers of air every one ortwo days. Installations consisting of several of the present inventioncan accomplish this level of air cleaning.

Other researchers have proposed the use of filters for removingparticulate matter from the air. However, because of the very largequantities of air that must be processed in large scale systems, theenergy requirements to force the air through the filters would beenormous. Replacement and disposal of filters would be labor intensiveand expensive. Additionally, the processed air would have about the samedensity as the dirty air, making it difficult to prevent immediatemixing of the two, unless suitable prevailing winds are present.

The present invention, although it requires substantial structure,accomplishes the cleaning of pollutants from the air usingstraightforward applications of natural forces. That is, water spraysprecipitate out the pollutants, and the evaporation of the water createsstrong winds through a chimney which pulls the air to be cleaned throughthe spray, and also can be used to drive turbines to produceelectricity.

It is therefore an object of the present invention to provide apparatuscapable of cleaning pollution products from large quantities of air.

It is another object of the present invention to provide apparatus whichcan, in addition to cleaning air, generate electricity, at least a partof which is used to pump water up to sprayers in a tower.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

SUMMARY OF THE INVENTION

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the apparatus of this invention comprises a convection tower forcleaning polluted air and generating electrical power comprising astructure having a tower section and a skirt section, the skirt sectionbeing formed into individual tunnels, and one or more first watersprayer means disposed in the tower section for providing fine mistwater droplets for evaporative cooling of air in the tower section ofthe structure to create a flow of the air through the structure and forremoving pollution from the air. A plurality of turbine generator meansare in the tunnels of the skirt section of the structure for generatingelectrical power from the flow of the air through the structure, and aplurality of second water sprayer means are disposed in the tunnels forremoving any remaining pollutants and the fine mist water droplets fromthe flow of air through the structure.

In a further aspect of the present invention, and in accordance with itsobjects and purposes, apparatus for cleaning pollution from air andproviding fresh water comprises a structure having a first tower and asecond tower connected by a conduit, the first tower being taller thansaid second tower, the second tower having a bottom and a top, and oneor more first water sprayer means located in the first tower forproviding fine mist water droplets for evaporative cooling of the air inthe tower section of the structure to create a flow of the air throughthe structure and for removing pollution from the air. Turbine generatormeans are disposed in the conduit for generating electrical power fromthe flow of the air through the structure. Second water sprayer meansare disposed in the conduit for removing any remaining pollutants andthe fine mist water droplets from the flow of air through the structure,and third water sprayer means are disposed in the second tower forproviding fresh water drops to collect mist particles that havecondensed from the flow of the air through the structure. Fresh watercollection means are located in the bottom of the second tower forcollecting fresh water from the second tower.

In a still further aspect of the present invention, an updraftconvection tower for use in areas having high humidity and for cleaningpolluted air and generating electrical power comprises a structurehaving a tower section with a top and a bottom, and a skirt sectionformed into a plurality of individual tunnel sections, and solar heatingmeans in the plurality of individual tunnel sections for preheating airin the plurality of individual tunnel sections and helping to create aflow of the air through the structure. A plurality of first watersprayer means are disposed in the skirt for removing pollution from theflow of air through the structure and for increasing the humidity tosaturation. A plurality of turbine motor/generator means are disposed inthe plurality of individual tunnel sections for initiating a flow of airand for generating electrical power from the flow of the air through thestructure. A second water sprayer means is located in the tower sectionfor producing water drops which collect mist particles in the flow ofthe air through the structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand, together with the description, serve to explain the principles ofthe invention. In the drawings:

FIG. 1 is a schematical cross-sectional side view of the downdraftembodiment of the present invention.

FIG. 2 is a schematical cross-sectional view of a tower constructionmethod using beams together with guy wires and cables to support afabric tower and skirt section.

FIG. 3 is a partial side view of the skirt section of the embodiment ofthe invention illustrated in FIG. 1, showing the detail of theindividual tunnels.

FIG. 4 is a schematical cross-sectional side view of the embodiment ofthe invention which, in addition to cleaning the air and generatingelectricity, produces fresh water.

FIG. 5 is a schematical cross-sectional side view of the embodiment ofthe invention which can operate in an updraft mode.

DETAILED DESCRIPTION

One embodiment of the present invention is illustrated schematicalcross-section in FIG. 1. Here, structure 10 comprises tower section 11and skirt section 12. Although designs for structure 10 can varygreatly, it should be understood that the cross-sectional area of towersection 11 could be made equal to the cross-sectional area of skirtsection 12 so that the air flow through structure 10 is unimpeded. Asseen, water sprayers 13, 14 in tower section 11 spray water, such as seawater or treated and chlorinated sewer water, down through tower section11 in the form of fine mist water droplets. The air in tower section 11is cooled by the evaporation of this water, and the water dropletssimultaneously absorb pollutant materials in the air. As the air iscooled, it becomes more dense than the ambient air, and falls downthrough tower section 11. As it falls, the air compresses and increasesin temperature, tending to lower the relative humidity in tower sectionWater drops continue to evaporate, tending to keep the relative humiditynear 100%.

Water drops which have not evaporated, and most particulates, are caughtin catch basin 15, as the fast moving air is passed through turbinegenerators 18 in skirt section 12 to generate electrical power. Anyparticulates and fine mist water droplets from water sprayers 13, 14which may have remained in the air flow are then removed by watersprayers 16 and collected in catch basins 15, so that the particulatesare not blown out as another pollutant into the surrounding air.Additional sprayer banks spraying other chemicals that dissolvehydrocarbons and other gases could also be installed in skirt section12.

The cleaned air which is output through skirt section 12 is cooler andmore dense than the ambient air, so that it spreads out near the groundand displaces polluted air upward so that it will enter tower section 11and be cleaned. A series of such towers around a city would create acool, clean layer of air near the surface, where the city's populationlives.

In one embodiment, illustrated in a schematical cross-sectional view inFIG. 2, structure 10 can be constructed by placing about ten steeltowers 21 around its circumference. Each steel tower 21 would besupported by guy wires 22 running radially outward. Other cables 23 runfrom each tower to the steel tower directly across, and fabric surface24 of structure 10 is stretched between steel towers 21 and over cables31, to form tunnels. Fabric surface 24 needs to be light, but strong.One possible fabric is Teflon® coated fiberglass, which is fireproof,chemical resistant, and has a probable life of 40 years. Also shown inposition are turbine generators 18.

Computer simulations for a structure 10 according to the presentinvention that has a height of 500 meters, and a radius of 200 meters,with an ambient temperature of 30° C., and relative humidity of 50%,have been run. They indicate that the differenoe in air density betweenthe air inside tower section 11 and the ambient air would create adownward wind in tower section 11 having a velocity of 25 mph. A totalof 121 cubic kilometers of air per day would be processed. Turbinegenerators 18 would be designed to extract 85 MW from the air stream.For this case, about 15,000 kg/sec of water would be required, and thepumping load would be in the area of 60 MW.

Generally, the rate of air flow through tower section 11 is determinedby the ambient temperature and relative humidity. A temperature of 3° C.and relative humidity of 20% would result in a doubling of the powerlevel obtained in the preceding simulation. Additionally, the flow rateis affected by the rate of flow of water through sprayers 13, 14, and16.

FIG. 3 is a partial side view of skirt section 12 illustrating thearrangement of fabric surface 24 to direct the air flow through turbinegenerators 18. Fabric surface 24 is stretched over cables 31 to formindividual tunnels 32, each tunnel 32 containing a turbine 18 andsprayers 16. As air passes through tower section 11 (FIG. 1) it isdirected into tunnels 32 and turns turbine generators

This embodiment benefits from the fact that structure 10 with its skirtsection 12 defines diffusers downstream from turbine generators 18.These diffusers result from the fact that the cross-sectional area intunnels 32 increases downstream of turbine generators 18. By havingdiffusers downstream of turbine generators 18 in the airflow, theefficiency of turbine generators 18 is increased. The diffuser effect ofthis embodiment of the present invention can be enhanced by raising thetop surface of skirt section 12 that lies beyond turbine generators 18.Enhancement of the diffuser effect would be possible if tunnels 32opened directly into the total area under a flat skirt section 12.Diffusers, commonly used with gas turbine engines, can significantlyincrease air velocity and kinetic energy in the present embodiment.

Another embodiment is illustrated in FIG. 4, where a convection towerarrangement is illustrated which, in addition to cleaning polluted airand generating electricity, can produce fresh water. Referring to FIG.4, there can be seen towers 40 and 41, connected together at theirbottoms by conduit 42. Sprayers 43 are located at the top of tower 40and sprayers 44 are located in conduit 42. Sprayers 43, 44 can sprayeither sea water, or treated and chlorinated sewer water in the form offine mist water droplets. Sprayers 45 are located at the top of towerwhich is shorter than tower 40. Sprayers 45 spray only fresh water.

As an alternative to the use of conduit 42, tower 41 could be madeconcentric with tower 40, with a larger diameter. A passage way for airis provided between the base of tower 40 and the base of tower 41.

In operation, sea water or treated and chlorinated sewer water issprayed through sprayers 43 and sprayers 44 as in the previousembodiment, causing the cooled air to descend through tower 40 andgenerate power in turbine generators 46, as in the previous embodiment.However, here, airflow 47 is through turbine generators 46 and intotower 41 through conduit 42. The sea water or treated and chlorinatedsewer water is collected in catch basin 48a. After passing throughturbine generators 46, the air passes through another sea water ortreated and chlorinated sewer water spray from sprayers 44 to removemost of any particulates and fine mist water droplets remaining the airat that point which are collected in catch basin 48b. As the air risesin tower 41, it cools, and becomes supersaturated with water vapor. Thevapor condenses on remaining particulate matter.

Additional condensation forms as the air continues flowing upward intower 41, but the mist particles are not sufficiently dense to fallthrough the rising air. However, at the top of tower 41 sprayers 45spray fresh water into the upward flowing air, and these water drops aresufficiently dense to fall through the air, collecting mist particles asthey fall. Fresh water is collected in catch basin 48c.

With tower 40 1000 meters tall and 200 Meters in radius, and tower 41500 meters tall and with a 200 meters radius, and at a temperature of30° C. and relative humidity of 50%, this embodiment could produce 22million 5 gallons of fresh water in 10 hours. The overall air cleaningand power production are similar to the previous embodiment. Instead ofbuilding towers, large inflated double-walled plastic tubes could belaid on the side of steep mountain slopes.

Another embodiment of the present invention is illustrated in FIG. 5.This embodiment is intended for areas of relatively high humidity, andis intended to operate in an updraft mode, similar to the processes incumulonimbus clouds. As seen, in this case, air enters at the bottom oftower 50 through skirt section 51, the flow of air being initiated byturbine motor/generators 53 operating in the motor mode to pull in theair. A portion of skirt section 51 can be made of transparent plastic inorder to trap available solar energy and help with the air flow. As theair near the ground is already heated by the sun, the effective area ofskirt section 51 is larger than the actual diameter of skirt section 51.

With the air flow established, the heated air flows through skirtsection 51 and through a spray of sea water or treated and chlorinatedsewer water from sprayers 52 where the pollution is removed, and thenthrough turbine motor/generators 53, now operating as generators, forpower production. The air is at nearly 100% relative humidity as itenters tower 50 and cools as it rises, the water vapor condensing into afog. However, this condensation releases heat which causes the air toexpand, making it less dense than the air outside tower 50, andproviding the buoyant force that drives the column of air upward.

At the top of tower 50, sprayers 54 spray fresh water which collects themist particles. The fresh water is collected in catch basin 55.Demisters could be used instead of water sprayers at the top of tower50.

Tower 50 needs to be taller than tower 11 of FIG. 1. Computersimulations indicate that a tower 50 having a height of 2000 meters and200 meters radius at a temperature of 30° C. and 90% relative humiditycould process 4 cu. km. of air per hour, and produce 20 MW of electricalpower and fresh water. Preheating the air increases the efficiency ofthis embodiment, as does higher humidity. As with the last embodiment,large inflated double-wall plastic tubes could be placed on steepmountain slopes, obviating the need for towers.

It will be recognized by those with skill in this art that, althoughsalt water and treated and chlorinated sewer water have been suggestedfor use in certain sprayers, any available and economical water may beused. Also, it should be understood that, when advantageous to do so,chemicals which are effective to dissolve hydrocarbons and other gasescould be sprayed into the airstream. In the cases where fresh water isspecified, it must be used to attain the full attributes of the variousembodiments.

The foregoing description of the embodiments of the invention have beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and obviously many modifications and variations are possiblein light of the above teaching. The embodiments were chosen anddescribed in order to best explain the principles of the invention andits practical application to thereby enable others skilled in the art tobest utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto.

What is claimed is:
 1. A convection tower for cleaning polluted air andgenerating electrical power comprising:a structure having a towersection integral with and a skirt section, said skirt section beingformed into individual tunnels; one or more first water sprayer meansdisposed in said tower section for providing fine mist water dropletsfor evaporative cooling of air in said tower section of said structureto create a flow of said air downward through said structure and forremoving pollution from said air; a plurality of turbine generator meansin said individual tunnels of said skirt section of said structure forgenerating electrical power from said flow of said air through saidstructure; and a plurality of second water sprayer means disposed insaid individual tunnels of said skirt section of said structure forremoving any remaining pollutants and said fine mist water droplets fromsaid flow of air through said structure.
 2. The convection tower asdescribed in claim 1, wherein said structure is comprised of fabricstretched between steel beams and cables.
 3. The convection tower asdescribed in claim 1, further comprising chemical sprayer means forspraying chemicals effective to dissolve hydrocarbons and other gasesfrom said flow of air through said structure.
 4. The convection tower asdescribed in claim 1, further comprising catch basin means forcollecting pollution particulates and water from said sprayers means.